In this study, Polylactic Acid (PLA) nonwoven fabric and thermoplastic polyurethane (TPU) honeycomb air cushion (TPU-HAC) were employed to form animpact resistant layer for functional knee pads. PLA nonwoven fabric has low
manufacture cost and flexibility of the honeycomb air cushion improved the quality of functional knee pad sold in the market.
This study focused on the strength of PLA nonwovens and the impact resistance of TPU honeycomb air pads. The PLA fibers
and low-melting-point (low-Tm) PLA fibers are used as raw materials to fabricate PLA nonwoven fabric. The PLA fibers
and low-melting-point PLA fibers were mixed at weight ratios of 10, 20, 30, 40, and 50 %. PLA nonwoven fabric and TPUHAC materials were combined in a sandwich structure to protect against impact. Impact resistance was evaluated using a falling- weight impact-resistance machine. Experimental findings indicate that changing various layers can improve the impact
resistance of the sandwich structure of the TPU-HAC materials. A TPU-HAC layer with a thickness of 2/8/10 mm optimized
the impact resistance. In 25 J falling-weight impact test, the TPU-HAC layer 2/8/10 mm provides an impact resistance of
2932 N; the PLA/TPU-HAC composite had the best impact resistance; 2516 N. PLA nonwoven fabric had the best mechanical properties with low-Tm PLA fibers at 30 % weight. The impact resistance achieved using above combination of materials
met the level 2, range 3 impact values mentioned in EN 14120 standards.